Dimethylammonium iodide stabilized bismuth halide perovskite photocatalyst for hydrogen evolution
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ronmental and Chemical Engineering Research Unit, University of Oulu, P. O. Box 4300, FI-90014 Oulu, Finland ELI-ALPS, ELI-HU Non-Profit Ltd., Dugonics ter 13, 6720 Szeged, Hungary 3 Institute of Physics, University of Szeged, Dóm tér 9, H-6720 Szeged, Hungary 4 Nano and Molecular Systems Research Unit, University of Oulu, P.O. Box 3000, FI-90014 Oulu, Finland 5 Optoelectronics and Measurement Techniques Unit, University of Oulu, FI-90570 Oulu, Finland 6 Microelectronics Research Unit, University of Oulu, P. O. Box 4500, FI-90014 Oulu, Finland † Present address: VTT Technical Research Centre of Finland, FI-90590 Oulu, Finland 2
© The Author(s) 2020 Received: 24 August 2020 / Revised: 30 September 2020 / Accepted: 4 October 2020
ABSTRACT Metal halide perovskites have emerged as novel and promising photocatalysts for hydrogen generation. Currently, their stability in water is a vital and urgent research question. In this paper a novel approach to stabilize a bismuth halide perovskite [(CH3)2NH2]3[BiI6] (DA3BiI6) in water using dimethylammonium iodide (DAI) without the assistance of acids or coatings is reported. The DA3BiI6 powder exhibits good stability in DAI solutions for at least two weeks. The concentration of DAI is found as a critical parameter, where the − I ions play the key role in the stabilization. The stability of DA3BiI6 in water is realized via a surface dissolution–recrystallization − process. Stabilized DA3BiI6 demonstrates constant photocatalytic properties for visible light-induced photo-oxidation of I ions and −1 with PtCl4 as a co-catalyst (Pt-DA3BiI6), photocatalytic H2 evolution with a rate of 5.7 μmol·h from HI in DAI solution, obtaining an apparent quantum efficiency of 0.83% at 535 nm. This study provides new insights on the stabilization of metal halide perovskites for photocatalysis in aqueous solution.
KEYWORDS bismuth halide perovskite, dimethylammonium iodide, photocatalysis, hydrogen evolution
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Introduction
Hydrogen evolution from solar-driven splitting of water or acids has been regarded as a promising approach for the conversion and storage of solar energy, and thus it has been under the scope of research for nearly half a century [1–3]. Until today, the typical photocatalysts have been rather inefficient because of their large band gap or severe recombination of photocarriers [4, 5]. More recently, metal halide perovskites have been widely employed as efficient photoactive materials in solar cells, with a surge of power conversion efficiency from 3.8% to exceeding 25.2% over the past decade [6, 7]. The exceptional performance in solar cells originates from their superior optoelectronic properties, such as wide absorption window and long electron–hole diffusion lengths [8–10], which are also highly expected among photocatalysts. For the first time, Nam et al. reported their pioneering work of photocatalytic hydroiodic acid (HI) splitting using methylammonium lead iodide (MAPbI3) [11]. To date, because of the instability of hybrid perovskites in water, all photocatalytic hydrogen
